How to answer brainteaser interview questions

Brainteasers. They’re the interview questions you can’t prepare for. Sometimes, they don’t have a right answer, which can be scary. The good news, though, is that there isn’t necessarily a wrong answer either. The key is thinking on your feet. Your interviewer will usually be more interested in how you approach the question, not what you answer.

We’ve put together some tips on how to answer different brainteaser questions:

• Old-school brainteaser questions
• Estimation questions
• Real-world questions
• Communication questions
• Odd interview questions

“You have a wolf, a goat and a cabbage, and you’re trying to cross a river. There’s a rowing boat big enough for you and one other thing. You can take as many trips as you like but you can’t leave the wolf alone with the goat, or the goat alone with the cabbage. How do you get everything across safely?”

If you’ve come across this one before, you’ll know the answer. If not, you’re probably confused. Don’t worry if this type of question flummoxes you as it’s going out of fashion. Old-school brainteasers aren’t particularly helpful to interviewers. You’ll either get the answer or you won’t, and some of that will be down to luck (ie. whether you’ve heard it before). They don’t tell employers much about you. If a question like this does come up, the point is to make you sweat. So, bring a notepad, jot down your thoughts and stay calm.

Oh, and if you’re wondering, you take the goat across the river first.

How many six-year-olds are there in Utah?

How many grains of sugar fit in a teaspoon?

To answer these questions, you need a combination of basic maths, educated guesswork and common sense. The point is to get to a vaguely plausible estimate by an appropriate method.

For the six-year-olds question, you need to find sensible ways to estimate the population of Utah and then the percentage of six-year-olds in the general population.

The real point is that you mustn’t say “I don’t know.” Your interviewer knows that already. They also won’t provide extra information, so don’t say “Can you tell me the population of the US overall?”

Feel free to write things down to help you reach an estimate. However, it’s important to think aloud so your interviewer understands your approach. They’re interested in hearing your logic, so give them a running commentary of your workings rather than skipping straight to a number.

What happens when you light a candle in zero gravity?

The answer is that the flame forms a slow-burning globe around the wick. However, an interviewer isn’t testing your science knowledge here. Once again, they want to know how your brain works.

Interviewers ask random real world questions, like “Why is a tennis ball fuzzy?” or “Where do albatrosses sleep?”, to get you to think logically through a topic you probably haven’t considered before.

It’s all about the approach so you’ll need to think aloud. List as many viable possibilities as you can and then compare them to see which is the most likely.

Someone needs to use your washing machine while you’re out. You don’t speak the same language. What instructions do you leave for them?

How would you explain supply and demand to a small child?

While a lot of brainteaser questions are mostly about seeing how you respond to the pressure of the question, communication-focused brainteasers are typically the ones where your answer tells the interviewer the most useful information. This type tests specific skills – communication and relating to others. You need to judge the other person’s needs and tailor your explanation accordingly.

Take a few moments of quiet before you tackle a communication question. Think carefully about your audience in the fictional scenario and how you’d best get your points across.

Some brainteaser interview questions are just plain weird. For example:

If you were an ice cream flavour, what would you be?

Would you rather fight a hundred duck-sized horses or one horse-sized duck?

How would you paint London purple?

These are the kind of questions that might come up when you chat with your mates, just for fun. And sometimes, that’s the point. As well as testing whether you can roll with the punches, these show how you’ll fit into the company culture. Are you relaxed or intense? Thoughtful or funny?

Just be yourself. So, go with the flow and say what comes naturally to you. There’s no need to overthink it. Your interviewer won’t hold it against you if you say you’d be mint choc chip and then they find out your favourite flavour’s strawberry.

A lot of interviewers find brainteaser questions unhelpful, so you may not encounter one. Even if you do, it won’t count for all that much compared to the questions about your skills and talents. However, it’ll still ease your interview nerves if you know what to do if one comes up.

The key thing is to stop fretting about getting it right because, sometimes, there’s no right (or wrong) answer. Instead, say what you’re thinking – including your workings out – and you’ll be fine.